In the experiment i attached different weights to a spring and measured the spring first as it was stretched and I then released the spring to see the highest and lowest points. I now am supposed to calculate the force in Newtons for each trial.

2. Relevant equations
F=ma I know is the equation for force but how is it applicable to this data? I understand m would be equal to the mass of the object in kg, but how would I find a for the equation?

3. The attempt at a solution
I originally thought that I would use the stretched spring as a, but now I am not so sure, would I use the change in the highest and lowest point instead? however, acceleration really doesn't apply here so I am confused.

In the experiment i attached different weights to a spring and measured the spring first as it was stretched and I then released the spring to see the highest and lowest points.

Please clarify that. When you released the spring, there were no weights left on it? And you measured the highest point it reached when it bounced back (and it continued to oscillate?).
If so, that's not good. The mass of the spring has become important.
What force are you trying to calculate? The force when the spring was loaded was the weight acting under gravity. Are you trying to estimate g? You'll need the spring modulus in that case.